(1)
x+1 2
x=1 3
3 4
x=5 6
3 4
x×5 6
=6 5
×3 4
6 5
x=
9 10
(2)17-120%x=5
17-1.2x=5
17-1.2x+1.2x=5+1.2x
5+1.2x=17
5+1.2x-5=17-5
1.2x=12
1.2x÷1.2=12÷1.2
x=10
(3)x-12%x=2.816
0.88x=2.816
0.88x÷0.88=2.816÷0.88
x=3.2
(4)
×4 5
-1 4
x=1 2
1 20
-1 5
x=1 2
1 20
-1 5
x+1 2
x=1 2
+1 20
x1 2
+1 20
x=1 2
1 5
+1 20
x-1 2
=1 20
-1 5
1 20
x=1 2
3 20
x×2=1 2
×23 20
x=
3 10